Data surge protection module

ABSTRACT

A data surge protection module which can be added to data and control networks not having such protection. The use of quick connect/disconnect connectors allows the rapid installation or replacement of such modules. a built in ground plate and a braided low impedance conductor offer alternative grounding methods for the module. The module employs two or more diode steering bridges and uses a diode as the surge suppression element.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention is directed to the field of electrical voltagesurge protection and more particularly to providing surge protection fordata communication circuits.

[0003] 2. Description of the Prior Art

[0004] Prior art surge protectors for programmable logic controllers(PLC's) or similar devices, are complex to use and require theattachment of various grounds, conductors and jumpers to protect datacommunication circuits. This makes the replacement of the surgeprotector difficult and time consuming.

SUMMARY OF THE INVENTION

[0005] The instant invention overcomes the difficulties noted above withrespect to the prior art. The instant invention employs a housing withtwo complementary ground connects. The first is a notched plate capableof accepting the shaft of an attachment bolt. This bolt fastens thehousing ground plate to a ground system. The second ground connection isimplemented via a low inductance ground strap. The ground strap is usedwhen dimensional constraints prevent the direct bolting of the notchedplate to a ground system. The input data conductors are coupled to aplug-in connector which is received in a suitable header on the housing.The output data conductors are also coupled to a plug-in connector whichis received in a suitable header on the housing. The use of the plug-inconnectors makes the connection to and from the module quick and easy. Anumber of diode steering bridges couples selected lines to a siliconavalance diode (SAD) which provides surge protection to one another toprotect against surges, line to line, and line to ground. The SADmounted at the bridge output is the surge suppression element fortransient voltage surges. Certain of the input data lines are also fusedwith automatically resettable positive temperature co-efficient devicescontained in the housing.

BRIEF DESCRIPTION OF THE DRAWING

[0006] In the drawings in which similar elements are given similarreference characters:

[0007]FIG. 1 is a front elevational view of a programmable logic device,hereafter “PLC” and a plurality of side card modules in an enclosure;

[0008]FIG. 2 is a front elevational view of the device of FIG. 1, withan electrical voltage surge protection module attached to the enclosurebut turned 90° to better illustrate the connections to the module.

[0009]FIG. 3 is a side elevational view of the enclosure of FIG. 2 witha module attached and grounded by means of a ground plate on the moduleand a ground strap on the enclosure.

[0010]FIG. 4 is a side elevational view of the enclosure of FIG. 2 witha module attached and grounded by means of a pigtail of braided metalcoupled to the enclosure.

[0011]FIG. 5 is an exploded, perspective view of the module and itsquick connect/disconnect connectors for three data input lines and threedata output lines.

[0012]FIG. 6 is an exploded, perspective view of the module and itsquick connect/disconnect connectors for six data input lines and sixdata output lines.

[0013]FIG. 7 is a top plan view of the printed circuit board (hereafter“PCB”) for a three data line module.

[0014]FIG. 8 is a side electrical view of the PCB of FIG. 7.

[0015]FIG. 9 is a top plan view of the PCB for a six data line module.

[0016]FIG. 10 is a side elevational view of the PCB of FIG. 9.

[0017]FIG. 11 is an exploded side elevational view of a module accordingto the invention.

[0018]FIG. 12 is a schematic drawing of a circuit for protecting amodule with three data lines.

[0019]FIG. 13 is a schematic drawing of a circuit for protecting amodule with six data lines.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Referring to FIG. 1 there is shown a PLC 24 mounted in a housing22 of signal loop network 20. Also mounted in enclosure 22 are a numberof “side card” modules 26 which act as input/output control devices. ThePLC 24 is connected to a mother board (not shown) across the back ofenclosure 22 and the individual side card modules, or daughter boards 26are connected to the mother board to receive operating voltages andsignals. The input lines 28, 30 and 32 from a computer or the like arecoupled to the PLC 24 and the output lines 34, 36 and 38 extend from thefirst side card module 26 to a circuit to the controlled. For exampleturning an electrical motor on or off. No surge protection is providedto the PLC or the side card modules 26 and they may be damaged ordestroyed by a transient voltage surge.

[0021]FIG. 2 shows the same arrangement of PLC 24 and side card modules26 in an enclosure 22 but with an electrical voltage surge protectionmodule 42 added to enclosure 22 to provide signal loop network 40. Lines28, 30 and 32 are removed from the input terminals of the PLC 24 and arecoupled to the input terminals 44, 46 and 48 of the module 42. Lines 50,52 and 54 are coupled between output terminals 56, 58 and 60 of themodule 42 and the input terminals of the PLC 24. This wiring of themodule 42 places it in series between the input lines 28, 30, 32 and theinput terminals of the PLC and provides transient voltage surgeprotection at this point.

[0022] Turning now to FIGS. 3, 4 and 11 the manner of mounting andgrounding the module 42 is shown. Module 42 has a PCB 62 (not shown)upon which the circuit components are located and to which is fastened abraided low impedance alternate ground wire 64. Also present on the PCB62 are two 3-pin headers or multi-pin connectors 66, only one of whichis visible in FIG. 11. For six conductor constructions two 6-pin headersor multi-pin connectors are used as will be explained below. The PCB 62is placed in a housing made up of a top housing portion 68 and a baseportion 70. A grounding plate 72 (FIG. 11) has a plug-in tongue 74 atone end and an upturned tab 76 at an opposite end. Tab 76 extendsthrough base portion 70 of the housing and into the PCB 62 where it issoldered to the PCB 62. The plug-in tongue 74 is best seen in FIG. 4 isattached via a volt 86 (as seen in FIG. 3). It is generally rectangularin shape and has cut-out 80 to provide two tongues 82 which can beplugged into a grounding stud 84 on the side of housing 22 as is shownin FIGS. 3 and 4. The module 42 is assembled by the use of two threadedfasteners 88 as shown by the dashed lines in FIG. 11.

[0023] The alternative ground attachment braided conductor 64 is notused in the arrangement of FIG. 3 and may be cut-off and discarded orcan be retained if desired. In the event no clearance space is availableto attach module 42 to the grounding stud 84 the module 42 may bemounted to the enclosure 22 or the grounding strap 84 by means ofbraided low impedance conductor 64. The conductor 64 is terminated in aconnector 86 which may be a ring terminal 86′ as shown in FIG. 5 or aspade terminal 86″ as shown n FIGS. 7 and 9. Connector 86 is held inplace by a suitable fastener. The module 42 can be fastened to enclosure22 by a crimp type fastener, bonding, pressure sensitive tape, braizing,welding or the like.

[0024] Referring to FIGS. 5 to 11 the module 42 for use with threeconductor cables and the module 42′ for use with six conductor cables inshown. The three pin header 66 has three vertical pins 90 which matewith three sockets (not shown) of a 3 pin quick connect/disconnectmulti-conductor connector or terminal connector 92. Conductors such as28, 30 and 32 can be fastened to a 3 pin terminal connector 92 using thescrew fasteners 94. In a similar fashion, the module 42′ has two six pinheaders 96 each with six vertical pins 98. The pins 98 mate with sixsockets (not shown) of a 6 pin quick connect/disconnect multi-conductorconnector or terminal connector 100. Conductors can be fastened to theterminal connector 100 by use of the screw fasteners 102.

[0025] Referring now to FIG. 12, the circuitry for a three conductorelectrical voltage surge protection module 42 is shown. A conductor 110extends from an imput J1-3 line 1-in terminal 112 to one side of a PTCfuse 114 rated at 10 amps at 250 volts. The other side of fuse 114 isconnected by conductor 116 to output terminal 118 marked schematicallyas J2-3 1-OUT. The conductors 110, 116 and fuse 114 constitute onesignal line from the computer or similar device to a PLC. Conductor 120extends from input terminal 122 marked J1-1 2-IN to one side of PTC fuse124. The other side of fuse 124 is connected by conductor 126 to outputterminal 128 marked J2-1 2-OUT. The conductors 120, 126 and fuse 124constitute a second signal line. A third line 130 extends from inputterminal 132 marked J1-2 SHLD to output terminal l34 marked J2-2 SHLD.This is the shield line conductor from the input cable that is passedthrough the device to the output cable and is grounded as at 136.

[0026] A first steering bridge 138 is made up of four diodes 140, 142,144 and 146. The anode of diode 140 is connected to the cathode of diode146 and to line 148 to conductor 116. The cathode of diode 140 isconnected to the cathode of diode 142 and to a line 150. The anode ofdiode 142 is connected to the cathode of diode 144, this junction isconnected to line 152 to conductor 126. Line 152 may be a single line ormade up of two sections jumpered together as at 154. The anode of diode144 is connected to the anode of diode 146. This junction is connectedto line 156. A SAD 158 is connected with its cathode connected to line150 and its anode connected to line 156. The SAD 158 provides thetransient voltage suppression for lines 110, 116 and 120, 126,respectively, as will be set forth below.

[0027] A second steering bridge 160 is made up of four diodes 162, 164,166 and 168. The anode of diode 162 is connected to the cathode of diode168. This junction is connected to line 170. The cathode of diode 162 iscoupled to the cathode of diode 164. This junction is connected to line150. The anode of diode 164 is connected to the cathode of diode 166.This junction is connected to line 170. Line 170 is connected byconductor 172 to shield line 130. The anode of diode 166 is connected tothe anode of diode 168. This junction is connected to line 156.

[0028] A positive transient voltage on line 110 greater than thebreakover point of diode 158 and less than current level of fuse 114will be conducted from terminal 112, conductor 110, fuse 114 to the line148 to the anode of diode 140. Diode 140 will conduct and place thistransient on line 150. The current with pass through the diode 158 fromcathode to anode and to line 156 and to the junction of the anodes ofdiodes 166 and 168. The transient is passed by lines 170 and 172 to theshield line 130 which is grounded, thereby shunting the excess transientcurrent to ground.

[0029] A negative transient voltage of sufficient magnitude on line 110from terminal 112 passes fuse 114 and is applied to line 148 and in turnto the cathode of diode 146. The transient then passes from the cathodeof diode 146 is applied to line 156, through the diode 158 from anode tocathode to line 150. The transient output on line 150 is divided by thediodes 162, 164 whose cathodes are connected to line 150 and anodes areconnected to line 170 then to line 172 to the grounded shield conductor130.

[0030] A positive transient voltage signal incurred to ground or betweenlines 120 and 122, line 120 passes from terminal 122, along line 120through fuse 124 to line 152. The signal continues from the anode to thecathode of diode 142 to line 150 to diode 158. The transient signal thenpasses through diode 158 from cathode to anode and to line 156. Line 156applies the signal to the anodes of diodes 166, 168. The cathodes ofdiodes 166 and 168 are each connected by line 170 to line 172 to thegrounded shield conductor 130.

[0031] A negative transient voltage signal incurred line 120 to groundbetween lines 120 and 122 passes through fuse 124 to line 152. Thesignal passes from cathode to anode of diode 144, to line 156 andthrough diode 158 from anode to cathode to line 150. The signal on line150 is applied to the cathodes of diodes 162, 164 whose anodes providesignals to transient lines 170, 172 to the grounded shield line 130.This arrangement provides transient voltage surge protection for line toline and line to ground surges.

[0032] The circuitry for a six conductor electrical voltage surgeprotection module 42′ is shown in FIG. 13. Line 180 from input terminal182 marked J1-6 TERM-IN is input to fuse 184 the output of which isconnected by conductor 186 to output terminal 188 marked J2-6 TERM-OUT.The conductors 180, 186 connect to an external resistor (not a part ofthis device) which terminates the module 42′ data line to the PLC.Conductor 190 extends from input terminal 192 marked J1-5 A-IN to fuse194 which is also connected to conductor 196 which extends to outputterminal 198 marked J2-5 A-OUT. This is a first signal line.

[0033] Conductor 200 extends from input terminal 202 marked J1-4 B-IN tofuse 204 and from fuse 204 via conductor 206 to output terminal 208marked J2-4 B-OUT which is the second signal line. Conductor 210 extendsfrom input terminal 212 marked J1-3 COMMON-IN to fuse 214, conductor 216to output terminal 218 marked J2-3 COMMON-OUT. This is the return linefor both of the signal lines A and B. From input terminal 222 markedJ1-2 SHLD-IN, conductor 220 connects to fuse 224 to conductor 226 tooutput terminal 228 marked J2-2 SHLD-OUT. A chassis ground line 230extends from input terminal 232 marked J1-l CHS-GND to output terminal234 marked J2-1 CHS-GND. Line 230 is tied to chassis ground 238 byconductor 236.

[0034] A first steering bridge 240 is composed of four diodes 242, 244,246 and 248. The anode of diode 242 is coupled to the cathode of diode248 and to line 250 connected at its other end to the common line 216.The cathode of diode 242 is connected to the cathode of diode 244 and toline 252. The anode of diode 244 is coupled to the cathode of diode 246and to line 254 coupled to the termination line 186. The anode of diode246 is coupled to the anode of diode 248 and to a line 256. A secondsteering bridge 260 is made up of four diodes 262, 264, 266 and 268. Theanode of diode 262 is coupled to the cathode of diode 268 and to a line270 connecting to the A-IN signal line 196. The cathode of diode 262 isconnected to the cathode of diode 264 and by line 272 to line 252. Theanode of diode 264 is connected to the cathode of diode 266 and line 274to the B-IN signal line 206. The anode of diode 266 is connected to theanode of diode 268 and by line 276 to line 256. A diode 278 has itsanode coupled to line 256 while its cathode is coupled to line 252.

[0035] A third steering bridge 280 is made up of four diodes 282, 284,286 and 288. The anode of diode 282 is coupled to the cathode of diode288 and to line 290 connected to shield line 226. The cathode of diode282 is connected to the cathode of diode 284 and to line 252. The anodeof diode 284 is connected to the cathode of diode 286 and by line 292 tochassis ground line 230. The anode of diode 286 is connected to theanode of diode 288 and by line 294 to line 256.

[0036] A positive transient voltage surge pulse incurred between inputterminal 182 and input terminal 222 or between 182 and 212 would passalong conductor 180 through fuse 184, line 254 to the anode of diode244, the cathode of diode 244 to line 252 to the cathode of the diode278. From the anode of the diode 278 the signal passes to line 256 tothe anodes of diodes 286, 288. The signal through diode 286 passes fromits anode to line 292 to chassis ground conductor 230 while the signalthrough diode 288 passes from its cathode to line 290 to shieldconductor 226. For terminal A-IN positive transient voltage surge pulsesincurred between 192 and 202 or 192 and 180 or 192 and 212 on terminal192. The transient is conducted along conductor 190 to fuse 194. Fromfuse 194 the transient travels along line 270 to the anode of diode 262,the cathode of diode 262 the line 272 to the line 252 and the cathode ofdiode 278. From the anode of diode 278 the pulse travels along line 256to the anodes of the diodes 286 and 288 whose cathodes steer thetransient to chassis ground line 230 and the shield line 226,respectively. For a transient pulse incurred between 200 and 190, 200and 210 or 200 and 180 the flow is via B-IN signal line 200 to inputterminal 202 to fuse 204 to 274 to the anode of diode 264 whose outputat the cathode is applied over line 272 to line 252 and through diode278 from cathode to anode to line 256. This signal divides betweendiodes 286 and 288, as explained above, and is coupled to the chassisground conductor 230 and the shield conductor 226. The application of atransient pulse to terminal 212 of conductor 210 is passed through fuse214 to the anode of diode 242, the cathode of diode 242, line 252 to thediode 278. The remainder of this circuit is the same as described withrespect to the A-IN signal line 196 described above. A surge transienton shield line 220 from input terminal 222 is coupled by fuse 224 toline 226 and by line 290 to the anode of diode 282, through diode 282 tothe line 252 and through the diode 278, cathode to anode to line 256 toline 294 to the anode of diode 286 and from the cathode of diode 286 tothe chassis ground conductor 230. The chassis ground line 230 isdirectly connected to an equipment ground and will ground any surgepulse applied to it.

[0037] A negative transient voltage surge pulse incurred between 182 and212, or 182 and 222 or 182 and 232 is conducted through conductor 180,fuse 184 to line 254, through diode 246 from cathode to anode, line 256to diode 278 where it passes anode to cathode to the cathodes of diodes282 and 284. The signal divides with a portion applied to each diode.The anode of diode 282 is coupled by line 290 to the shield line 226while the anode of diode 284 is connected by line 292 to the chassisground line 230. A negative transient voltage surge pulse incurredbetween 192 and 202, 192 and 222, 192 and 232 is conducted throughterminal 192 of the A-IN along conductor 190, through fuse 194 to line270 to the cathode of diode 268. From the anode of diode 268 the pulsetravels along line 276 to line 256 to diode 278 where it passes fromanode to cathode to the line 252 and the juncture between diodes 282,284 which operate in the same manner as set forth above with respect tothe termination line 186. A negative transient voltage surge pulseincurred between 202 and 192, 202 and 222, or 202 and 232 is conductedfrom B-IN to signal line 200 from terminal 202 is conducted through fuse204 to conductor 206. From conductor 206 it passes along line 274 to thecathode of diode 266, from the anode of diode 266 along line 276 to line256 to the diode 278. The further connections are as described above.When the common line 210 incurs a negative transient voltage surge pulsebetween 212 and 222 and 212 and 232 it is conducted via terminal 212 byfuse 214 to conductor 216. From conductor 216 the pulse passes alongline 250 to the cathode of diode 248, from the anode of diode 248 to theline 256 to the diode 278 and through the diodes 282 and 284 asexplained above. The presence of a negative surge pulse on the shieldconductor 226 from terminal 222 via fuse 224 and lines 226 and 290 isapplied to the cathode of diode 288. The diode conducts via its anode toline 294, line 256 to the anode of diode 278 which conducts anode tocathode and applies the transient to the cathode of diode 284 whoseanode is connected via line 292 to the chassis ground conductor 230. Anegative voltage surge pulse applied to the chassis ground conductor 230is directly connected to the system ground via line 236 and groundconnection 238. This circuit provides surge protection for line to line,line to shield and line to ground.

[0038] While there have been shown and described and pointed out thefundamental novel features of the invention as applied to the preferredembodiments, as are presently contemplated for carrying them out, itwill be understood that various omissions and substitutions and changesof the form and details of the devices illustrated and in theiroperation may be made by those skilled in the art, without departingfrom the spirit of the invention.

We claim:
 1. A data surge protection module for protecting datacommunication circuits from transient voltage surges, comprising: a) ahousing; b) a printed circuit board within said housing; c) a groundterminal plate coupled to said printed circuit board adapted forinsertion in a grounding strap on an enclosure; and d) a low impedanceground wire coupled to said printed circuit board and adapted to becoupled to said enclosure whereby one of said ground terminal plate andsaid low impedance ground wire is coupled to said enclosure to provide aground for said data surge protection module.
 2. A data surge protectormodule, as defined in claim 1, wherein said low impedance ground wire isa braided wire.
 3. A data surge protector module, as defined in claim 1,further comprising: a) a first multi-conductor connector coupled to alike number of data input conductors; and b) a first multi-pinconnector, one first pin for each of said data input conductors, each ofsaid first pins coupled to said printed circuit board whereby thejoining of said first multi-conductor connector and said first multi-pinconnector connects said data input conductors to said printed circuitboard.
 4. A data surge protector module, as defined in claim 3, furthercomprising: a) a second multi-conductor connector coupled to a likenumber of data output conductors; and b) a second multi-pin connector,one second pin for each of said data output conductors, each of saidsecond pins coupled to said printed circuit board whereby the joining ofsaid second multi-conductor connector and said second multi-pinconnector connects said data output conductors to said printed circuitboard and said data input conductors.
 5. A data surge protector module,as defined in claim 3, wherein said first multi-pin connector is a quickconnect, quick disconnect connector.
 6. A data surge protection module,as defined in claim 4, wherein said second multi-pin connector is aquick connect, quick disconnect connector.
 7. A data surge protectionmodule, as defined in claim 4, wherein both of said first multi-pin andsecond multi-pin connectors are quick connect, quick disconnectconnectors.
 8. A data surge protection module, as defined in claim 3,wherein said number of data input conductors is three.
 9. A data surgeprotection module, as defined in claim 3, wherein said number of datainput conductors is six.
 10. A data surge protector module, as definedin claim 8, wherein said number of data output conductors is three. 11.A data surge protector module, as defined in claim 9, wherein saidnumber of data output conductors is six.
 12. a data surge protectionmodule comprising: a) a housing; b) a printed circuit board within saidhousing; c) a first steering bridge on said printed circuit boardcoupled to a first data input conductor and a first data outputconductor and a second data input conductor and a second data outputconductor to direct electrical pulses between said first data inputconductor and said second data output conductor; d) a second steeringbridge on said printed circuit board coupled to said first steeringbridge and a third data output conductor; and e) a diode coupled acrosssaid first and second steering bridges.
 13. A data surge protectionmodule, as defined in claim 12, wherein said second data input conductoris coupled to said first data input conductor and to a grounded shieldand said third data output conductor is connected to said groundedshield whereby said data surge protection module is surge protectedbetween said first and second data output conductors and between each ofsaid first and second data output conductors and said third data outputconductor.
 14. A data surge protection module, as defined in claim 13,further comprising: a) a first fuse in said first data input conductor;and b) a second fuse in said second data input conductor.
 15. A datasurge protection module, as defined in claim 14, wherein said first andsecond fuses are resettable.
 16. A data surge protection module, asdefined in claim 14, wherein said first and second fuses are resettablepositive temperature coefficient fuses.